Circuits often contain voltage or current supplies that provide voltage or current to various components within the circuit. In some cases, circuits receive voltage or current from external supplies, and the externally-provided voltage or current is routed to components in the circuit. The circumstances in which a circuit permits the provision of voltage or current to a particular circuit component is often controlled using one or more switches. For example, a switch that is closed permits current flow through the switch and a switch that is open prevents current flow through the switch. Transistors, such as metal oxide semiconductor field effect transistors (MOSFETs), are a common type of circuit switch.